When a string of a stringed instrument is plucked, the string forms a special waveform by the vibration. In order to produce a clear sound without causing a buzzing sound or a problem in producing sound, it is necessary that the portion where the string comes into contact with the frets, the fretboard or the fingerboard, has a curve which complies with the movement of the string. The thickest string which produces the lowest key (marked as No. 10 in FIG. 4) forms the largest curve (marked as No. 11 in FIG. 4). Therefore, the curve formed by this thickest string is the deepest. Accordingly, the curve (marked as No. 13 in FIG. 4) formed by the thinnest string (marked as No. 12 in FIG. 4) is the shallowest.
A technique to accurately shape the frets (marked as No. 156 in FIG. 27), the fretboard (marked as No. 157 in FIG. 27) or the fingerboard (marked as No. 168 in FIG. 28) of a stringed instrument by hand, so as to provide them with a gradually altering curve, has not been known to public until now.
The tool according to the present invention can accurately adjust the curve of the tool itself, and can accurately shape the curve appropriate for the frets, the fretboard or the fingerboard of the stringed instrument, by polishing the surface thereof. The tool according to the present invention provides good results, since the operation can be conducted with the strings on, without disturbing the perfect balance for the stringed instrument.
Regarding a stringed instrument having frets, it is necessary to level the frets so that the instrument functions well and smooth performance is achieved. Leveling frets has always been conducted in the condition where the surface of the frets is made linear as possible. The surface is made linear by adjusting the neck of the stringed instrument.
After leveling is conducted, the neck is adjusted again in order to apply a slight curve to the neck, and thus the curve of the neck complies with the movement of the strings. Further, a standard technique for leveling frets assumes removal of the strings in order to allow the tool to reach the fretboard.